Slide lock for hatch on gas containment cover

Abstract

A hinged hatch in a gas containment cover particularly for a sewage treatment tank has a slide bolt contained within a shaped channel of an extrusion of the hatch, positioned to engage the bolt at a mid-level position of the adjacent fixed beam or other member of the tank cover. The position of the bolt enables the hinged hatch to fully seal against a rubber-covered lip of the adjacent structural member, so that the bolt latch does not compromise integrity of the gas seal. As the bolt is slid into locking position it forces the hatch cover down more tightly against the gas seal.

We claim: 
     
       1. In a fixed tank cover on a gas-containing tank, the tank cover being formed of assembled aluminum extrusions including slats secured together at edges and retained in channel members at ends, and including at least one liftable access panel within the fixed tank cover, a latch system for the access panel configured to preserve a gas seal at an edge of the access panel when closed, comprising:
 the access panel being formed of a plurality of parallel deck slats interlocked edge to edge, with ends of the deck slats retained in a framing channel member at one side of the access panel, and the access panel having a liftable end, perpendicular to said one side, that bears down against an adjacent fixed surface of the fixed tank cover in sealed relationship therewith, 
 a fixed structure adjacent to said one side of the access panel, the fixed structure comprising a beam of the fixed tank cover, the beam having a ledge which is continuous along a length of the access panel and extends under a bottom surface of the framing channel member, with a flexible gasket sealed between the ledge and said bottom surface when the access panel is closed and rests on the gasket seal, providing said gas seal between the access panel and the fixed structure, 
 at said one side of the access panel the framing channel member having an opening above said bottom surface, 
 one of the plurality of parallel deck slats of the access panel having an extruded capturing channel having a side opening forming an elongated continuous slot, the capturing channel being aligned with the opening in the framing channel member, with a bar latch positioned slidably in the capturing channel and including a gripping handle secured to the bar latch and extending out of the capturing channel through the elongated continuous slot permitting the gripping handle to be gripped by a user to slide the bar latch outwardly to extend through the opening of the framing channel member and outwardly from the access panel, 
 and said beam of the fixed tank cover having a recess aligned with the bar latch when the access panel is closed, to receive the bar latch when extended and thus to latch the access panel to the beam of the fixed tank cover to prevent opening of the access panel, the recess comprising an extruded channel formed in the side of the beam and having an open side facing the bar latch, so as to receive the bar latch, the channel having a sloped upper surface to force the access panel downwardly against the gasket seal as the bar latch is pushed into a locking position, 
 whereby the gas seal is not compromised by the latch system, the slidable bar latch being positioned above said bottom surface of the framing channel member so as not to interrupt the gas seal between said bottom surface and said ledge. 
 
     
     
       2. The latch system of  claim 1 , wherein the bar latch is rectangular in cross section and the capturing channel is of a complementary shape for sliding of the bar latch in the channel. 
     
     
       3. The latch system of  claim 2 , wherein the gripping handle of the bar latch is a machine bolt in a threaded bore of the bar latch, the threaded bore extending diagonally through the rectangular bar latch, providing for tightening of the machine bolt to act as a set screw to hold the bar latch in position. 
     
     
       4. The latch system of  claim 1 , further including a compression spring within the capturing channel and positioned to urge the bar latch outward toward the locking position. 
     
     
       5. The latch system of  claim 4 , wherein the spring engages against a stop element positioned in the capturing channel. 
     
     
       6. The latch system of  claim 1 , wherein said one of the plurality of parallel deck slats with the extruded capturing channel includes an extruded handle adjacent to and formed parallel with the capturing channel.